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U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  124. 

L.  O.  HOWARD.  Entomologist  and  Chief  of  Bureau. 


THE  ROSE  SLUG-CATERPILLAR. 


BY 


F.  H.  CHITTENDEN,  Sc.  D, 

In  Charge  of  Truck  Crop  and  Stored  Product  Insect  Investigations. 


Issued  October  31,  1913. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1913. 


U.  S.  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  124. 

L.  O.  HOWARD.  Entomologist  and  Chief  of  Bureau. 


THE  ROSE  SLUG-CATERPILLAR 


BY 


F.  H.  CHITTENDEN,  Sc.  D., 

In  Charge  of  Truck  Crop  and  Stored  Product  Insect  Investigations. 


Issued  October  31,  1913. 


WASHINGTON: 

GOVERNMENT  PRINTING  OFFICE. 

1913. 


BUREAU  OF  ENTOMOLOGY. 

L.  O.  Howard,  Entomologist  and  Chief  of  Bureau. 

C.  L.  Marlatt,  Entomologist  and  Acting  Chief  in  Absence  of  Chief 

R.  S.  Clifton,  Executive  Assistant. 

W.  F.  Tastet,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  truck  crop  and  stored  product  insect  investigations. 

A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 

W.  D.  Hunter,  in  charge  of  southern  field  crop  insect  investigations. 

F:  M.  Webster,  in  charge  of  cereal  and  forage  insect  investigations. 

A.  L.  Quaintance,  in  charge  of  deciduous  fruit  insect  investigations. 

E.  F.  Phillips,  in  charge  of  bee  culture. 

A.  F.  Burgess,  in  charge  of  gipsy  moth  and  broirn-tail  moth  investigations. 

Rolla  P.  Currie,  in  charge  of  editorial  work. 

Mabel  Colcord,  in  charge  of  library. 

Truck  Crop  and  Stored  Product  Insect  Investigations. 

F.  H.  Chittenden,  in  charge. 

C.  H.  Popenoe,  Wm.  B.  Parker,  H.  M.  Russell,  H.  O.  Marsh,  M.  M.  High, 
John  E.  Graf,  Fred  A.  Johnston,  C.  F.  Stahl,  D.  E.  Fink,  A.  B.  Duckett, 
F.  B.  Milliken,  entomological  assistants. 

I.  J.  Condit,  R.  S.  Vaile,  collaborators  in  California. 

W.  N.  Obd,  collaborator  in  Oregon. 

Thos.  H.  Jones,  collaborator  in  Porto  Rico. 

Marion   T.   Van   Horn,  Pauline  M.  Johnson,  Anita  M.  Ballinger,   Cecilia 
Si sco,  preparators. 
2 


CONTENTS 

Page. 

Introduction    5 

The  moth 5 

The  egg 6 

The  larva 6 

The  pupa  and  cocoon 6 

Historical    7 

Life  history 8 

Remedies  9 


ILLUSTRATION. 


Fig.  1.     The  rose  slug-caterpillar  (Euclea  indetermina)  :  Stages 7 

3 

8885°— 13 


THE  ROSE  SLUG-CATERPILLAR. 

(Euclea  indetermina  Boisd.) 


INTRODUCTION. 

It  is  only  within  comparatively  recent  years  that  the  slug-like 
caterpillar,  Euclea  indetermina  Boisd.,  has  been  known  to  injure  the 
rose.  In  August,  1905,  the  Bureau  of  Entomology  received  two 
reports  of  attack  to  the  foliage  of  rosebushes  by  this  species.  The 
insect  has,  however,  been  previously  observed  to  have  this  food  habit. 

August  15,  1905,  Dr.  A.  D.  Hopkins  furnished  specimens  of  the 
larva  from  Kanawha  Station,  W.  Va.,  stating  that  a  dozen  or  more 
individuals  could  be  found  feeding  on  the  leaves  of  a  single  rosebush. 
B}^  August  20  the  specimens  received  had  transformed  to  pupae. 
During  the  last  week  of  August  the  same  species,  accompanied  by 
specimens  of  both  the  penultimate  and  last  stages,  was  received  from 
Mr.  S.  D.  Nixon,  with  report  that  it  was  injuring  roses  at  Balti- 
more, Md. 

The  rose  slug-caterpillar  has  been  figured  and  described  in  its 
various  stages,  but  is  not  a  common  species  and,  therefore,  not  well 
known.  It  is,  however,  strongly  and  attractively  marked  and  very 
interesting  in  its  transformations,  resembling  in  some  particulars  the 
more  common  and  related  saddle-back  caterpillar  ( \Emq>retid\  Sibine 
stimidea  Clem.).  The  accompanying  illustration  (fig.  1),  notes,  and 
brief  descriptions  have  been  brought  together  as  of  interest  to  rose 
growers  and  also  to  nurserymen,  for  the  caterpillars  also  attack 
young  trees  and  shrubs.  It  is  in  the  last  two  stages  of  its  larval 
existence  that  this  species  attracts  most  attention.  The  moth  which 
it  produces  is  less  often  seen. 

THE  MOTH. 

In  its  adult  stage  this  insect  is  nearly  as  attractive  as  the  larva. 
Its  coloration  is  unusual  in  the  boreal  American  fauna.  The  general 
color  is  pale  cinnamon  brown ;  the  f orewings  are  darker  and  crossed 
diagonally  by  a  green  band,  which  occupies  more  than  half  the 
wing,  leaving  a  wide  border  of  darker  brown  and  an  inner  or  basal 
area  of  the  same  color  and  of  the  form  shown  in  figure  1,  a.  The 
hind  wings  and  the  underside  of  the  wings  are  nearly  uniform  pale 
brown,  as  is  also  the  body,  except  on  the  edges  of  the  wings  and 
the  tip  of  the  abdomen.     The  thorax  is  like  green  plush.     The  wing 

5 


6  THE   ROSE    SLUG-CATERPILLAR. 

expanse  of  the  male  is  generally  a  little  less  than  an  inch;  of  the 
female,  a  little  more. 

The  moth  closely  resembles  (Parasa)  Euclea  Moris  H.-S.,  for 
which  it  has  often  been  mistaken.1 

THE  EGG. 

The  egg  is  described  by  Dr.  H.  G.  Dyar  as  follows : 

Singly,  or  in  small  groups,  slightly  imbricated.  Elliptical,  flattened,  translu- 
cent pale  ochre-yellow  on  glass,  1.5  by  9  mm. ;  reticulations  obscure,  possibly 
only  in  a  strong  light,  rounded  hexagonally,  nearly  linear,  somewhat  irregular. 
No  special  characters.     They  hatch  in  nine  days. 

THE   LARVA. 

The  following  is  descriptive  of  the  larval  forms  received  from 
West  Virginia  and  Maryland,  but  according  to  other  describers  the 
general  color  varies  from  red  to  sulphur-yellow. 

The  penultimate  stage. — In  the  penultimate  stage  the  larva  closely 
resembles  the  mature  form,  but  the  prominent  spine-bearing  processes 
are  paler  and  less  reddish,  being  chiefly  of  a  dull  lemon-yellow  color, 
with  the  exception  of  the  small  lateral  spiny  tufts,  which  are  orange 
at  the  base.  Between  the  third  and  fourth  processes  the  dorso-lateral 
stripes  are  distinctly  carmine.  The  length  of  the  slug-caterpillar  at 
this  stage  is  about  half  an  inch  or  a  little  more. 

The  full-grown  larva. — The  full-grown  larva  looks  very  unlike 
any  common  species  with  which  it  could  be  compared,  but  in  the 
general  arrangement  of  its  spines  it  resembles  Sibine  stimulea.  Its 
form  is  similar,  but  the  general  impression  as  to  color  is  orange, 
which  is  the  color  of  the  principal  spine-bearing  processes,  of  which 
there  are  seven  pairs,  as  follows:  Two  in  front,  two  behind,  one 
pair  in  the  middle,  a  shorter  pair  proceeding  from  the  first  thoracic 
segment  just  above  the  head,  and  the  seventh  pair  proceeding  from  the 
second  thoracic  segment  on  each  side.  There  is  a  dorso-lateral 
vermilion-scarlet  stripe  bearing  six  pairs  of  moderately  long  spinous 
processes  and  four  rosette-like  spinous  tufts.  There  is  also  a  lateral 
red  stripe  and  a  sublateral  red  stripe  bearing  nine  rosette-like  spi- 
nous tufts.  The  thin  violet  or  mauve  lines,  in  the  middle  of  the  back, 
as  shown  in  figure  1,  c,  alternate  with  white.  The  length  is  about 
three-fourths  of  an  inch. 

THE   PUPA   AND   COCOON. 

The  pupa  (fig.  1,  /)  is  so  similar  to  that  of  Sibine  stimulea  that  a 
detailed  description  is  not  necessary  for  present  purposes.  It  is  a 
trifle  smaller  than  the  latter,  and  in  its  early  stage  pale  yellow  with 

1  Beth  species  belong  to  the  family  Cochlidiidae. 


HISTORICAL.  7 

pale  brown  eyes  and  palpi.  It  measures  about  three-eighths  of  an 
inch  in  length.  The  hornlike  process  extending  above  and  between 
the  eyes  is  prominent. 

The  pupal  stage  is  passed  in  a  cocoon  (fig.  1,  g)  of  rounded  oval 
form,  looking  not  unlike  a  very  small  puffball.  It  is  chocolate  colored, 
of  firm,  nearly  parchment-like  consistency,  and  roughened  opaque  on 
the  outer  surface.  It  measures  about  four-tenths  of  an  inch  in  its 
longer  diameter  and  three-eighths  inch  in  the  shorter. 

HISTORICAL. 

Among  the  notes  of  the  Bureau  of  Entomology  is  one  copied  from 
Riley's  notebook  recording  the  occurrence  of  the  larvae  on  chestnut 
at  South  Pass,  111.,  in  August,  1869.  It  contains  a  good  description 
of  the  larva,  and  states  that  it  feeds  on  the  edges  of  the  leaves,  de- 
vouring every  particle  as  smoothly  as  if  cut  with  a  pair  of  scissors. 
Pupation  takes  place  about  September  20.  It  is  worthy  of  note  that 
Riley  was  of  the  opinion  that  the  end  of  the  lid  of  the  cocoon  was 


Fig.  1. — The  rose  slug-caterpillar  (Euclea  indetermina)  :  a,  Female  moth;  6,  male  an- 
tenna ;  c,  larva,  dorsal  view  ;  d,  larva,  lateral  view  ;  e,  spine  of  larva,  much  enlarged  ; 
/,  pupa;  g,  cocoon.     All  enlarged;  e,  greatly  enlarged.      (Original.) 

cut  by  the  larva  before  transformation  to  pupa,  while  it  is  quite 
obvious  that  the  cephalic  armament  of  the  pupa  is  designed  for  that 
purpose,  the  pupa  constantly  wriggling  around  and  around,  thus 
making  the  perfectly  circular  flap. 

October  7,  1883,  larvae  were  found  feeding  on  oak  in  Virginia,  and 
at  another  time  feeding  on  paw  paw  when  in  bloom  at  Point  of 
Rocks,  Md. 

August  3,  1889,  this  species  was  received  from  Vineland,  X.  J., 
where  it  was  taken  on  Kansas  plum. 


8  THE    ROSE    SLUG-CATERPILLAR. 

September  3,  1896,  the  insect  was  reported  feeding  on  the  leaves 
of  Japan  plum  at  Barnesville,  Schuylkill  County,  Pa. 

In  1897  Dr.  H.  G.  Dyar  published  a  very  full  account  of  the  life 
stages  of  this  species  and  gave  reference  to  its  literature.1  The  larva 
appears  to  have  been  known  as  long  ago  as  1797,  when  Smith  and 
Abbot  figured  it  in  connection  with  another  species  of  moth  to  which 
it  did  not  belong,  namely,  u  Limacodes  cippus."  Under  this  name 
the  species  is  mentioned  by  Harris.2  The  moth  was  not  described 
until   1832.3 

The  recognized  synonyms  of  Euclea  indetermina  are  as  follows: 
CaUochroa  viridis  Reak.,  C.  vernata  Pack.,  and  Parasa  chloris  Grote 
et  auct.  (non  H.-S.). 

As  remarked  by  Dr.  Dyar,  the  larva?  feed  on  various  kinds  of 
low-growing  bushes.  The  list  of  food  plants  observed  includes  rose 
{Rosa  spp.),  wild  cherry  (Prunus  spp.),  oak  (Quercus  spp.),  chest- 
nut (Castanea  dentata),  hickory  (Carya  spp.),  paw  paw  (Asimina 
triloba),  bayberry  or  wax  myrtle  (Myr'tca  cerifera),  flowering  dog- 
wood (Cornus  florida),  plum,  apple,  and  pear. 

LIFE    HISTORY. 

The  various  descriptions  which  have  been  furnished  of  this  species 
agree  in  many  easily  observable  particulars,  but  differ  somewhat  in 
detail.  All  writers  seem  to  agree  in  stating  that  the  larvae  mature 
during  September,  but  it  will  be  noted  that  the  specimens  which  were 
received  from  West  Virginia  had  matured  August  20. 

Eggs  are  deposited  during:  July,  in  small  groups  slightly  imbri- 
cating or  overlapping,  and  hatch  in  about  nine  days.  The  larvae 
generally  mature  toward  the  middle  of  September,  remaining  on  the 
underside  of  the  leaves — something  unusual  considering  their  con- 
spicuous coloration.  The  larva?  or  caterpillars  undergo  eight  dis- 
tinct stages,  and  occasionally  nine,  before  transforming  to  pupa?, 
and  it  has  been  observed  that  in  stage  I,  which  is  passed  rapidly. 
they  take  no  nourishment.  The  species  hibernates  in  its  cocoon,  and 
the  moth  has  generally  been  observed  to  issue  in  July. 

As  to  the  manner  of  forming  the  cocoon  in  confinement,  all  of  the 
cocoons  reared  by  the  writer  were  attached  to  some  object.  Mr.  M.  V. 
Andrews.4  who  reared  hundreds  of  this  species  in  confinement,  states 
that  in  all  cases  it  either  forms  its  cocoon  adherent  to  the  stem  of  the 
food  plant  or.  occasionally,  draws  two  leaves  together  for  a  shelter. 
There  appears  to  be  a  somewhat  general  agreement,  however,  that 
in  nature  the  cocoons  are  formed  on  the  ground  among  loose  rubbish. 

1  Journal  X.  Y.  Ent.  Soc,  vol.  5,  pp.  10-14,  pi.  2,  1897. 

-Harris.  T.  W..   Insects  Injurious  to  Vegetation,   Flint  ed.,   1862,  p.  421. 

8Boisduval,  Cuvier'a  Animal  Kingdom,  pi.  103,  flg.  8,  1832. 

4  Fsyche.  vol.  2,  p.  271,  1879. 


REMEDIES.  9 

This  species  is  of  equal  interest  with  the  saddle-back  caterpillar, 
-with  which  it  has  been  compared  in  previous  pages,  not  alone  on  ac- 
count of  its  beauty  in  all  stages  and  its  habits,  but  because  of  the 
indicating  or  stinging  spines  borne  by  the  caterpillars.  At  the  bases 
of  these  spines  are  glands  which  secrete  an  irritating  fluid  similar  in 
its  effect  to  that  of  nettles.  It  follows  that  rough  handling  of  the 
caterpillars  results  in  the  breaking  off  of  the  tips  of  these  spines, 
which  enter  the  skin  and  release  a  small  drop  of  the  irritating  liquid, 
producing  a  burning  sensation  which  varies  in  intensity  according  to 
the  person  exposed. 

REMEDIES. 

In  case  only  a  few  rosebushes  or  young  trees  are  attacked,  hand- 
picking  is  ample  for  controlling  this  insect,  the  precaution  being 
taken  to  use  a  glove,  thus  avoiding  being  c*  stung."  Should  the  cater- 
pillars occur  on  several  plants,  and  if  a  spraying  outfit  is  available 
which  may  be  used  without  danger  of  poisoning  to  human  beings,  a 
spray  of  Paris  green  or  arsenate  of  lead  may  be  applied. 


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